﻿<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> New Document < / TITLE>
<META NAME = "Generator" CONTENT = "EditPlus">
<META NAME = "Author" CONTENT = "">
<META NAME = "Keywords" CONTENT = "">
<META NAME = "Description" CONTENT = "">
<style>
html, body{
height: 100 %;
padding : 0;
margin : 0;
background: #000;
}
canvas{
  position: absolute;
  width: 100 %;
  height: 100 %;
}
< / style>
< / HEAD>

<BODY>
<canvas id = "c">< / canvas>
<script>
var c = document.getElementById("c");
var	ctx = c.getContext("2d");
c.width = window.innerWidth;
c.height = window.innerHeight;
//				ctx.fillRect(0,0,100,100);
//				a,b,c,d分别代表x方向偏移,y方向偏移,宽，高
var string1 = "abcdefghijklmnopqrstuvwxyz";
string1.split("");
var fontsize = 20;
columns = c.width / fontsize;
var drop = [];
for (var x = 0; x < columns; x++)
{
    drop[x] = 0;
}
function drap() {
    ctx.fillStyle = "rgba(0,0,0,0.07)";
    ctx.fillRect(0, 0, c.width, c.height);
    ctx.fillStyle = "#ea80b0";
    ctx.font = fontsize + "px arial";
    for (var i = 0; i < drop.length; i++) {
        var text1 = string1[Math.floor(Math.random() * string1.length)];
        ctx.fillText(text1, i * fontsize, drop[i] * fontsize);
        drop[i]++;
        if (drop[i] * fontsize > c.height && Math.random() > 0.9) {//90%的几率掉落
            drop[i] = 0;
        }
    }
}
setInterval(drap, 50);
< / script>
<canvas id = "pinkboard">< / canvas>
<script>
/*
* Settings
*/
var settings = {
  particles: {
    length:   500, // maximum amount of particles
    duration : 2, // particle duration in sec
    velocity : 100, // particle velocity in pixels/sec
    effect : -0.75, // play with this for a nice effect
    size : 30, // particle size in pixels
  },
};

/*
 * RequestAnimationFrame polyfill by Erik Möller
 */
(function() { var b = 0; var c = ["ms", "moz", "webkit", "o"]; for (var a = 0; a < c.length && !window.requestAnimationFrame; ++a) { window.requestAnimationFrame = window[c[a] + "RequestAnimationFrame"]; window.cancelAnimationFrame = window[c[a] + "CancelAnimationFrame"] || window[c[a] + "CancelRequestAnimationFrame"] }if (!window.requestAnimationFrame) { window.requestAnimationFrame = function(h, e) { var d = new Date().getTime(); var f = Math.max(0, 16 - (d - b)); var g = window.setTimeout(function() { h(d + f) }, f); b = d + f; return g } }if (!window.cancelAnimationFrame) { window.cancelAnimationFrame = function(d) { clearTimeout(d) } } }());

/*
 * Point class
 */
var Point = (function() {
    function Point(x, y) {
        this.x = (typeof x != = 'undefined') ? x : 0;
        this.y = (typeof y != = 'undefined') ? y : 0;
    }
    Point.prototype.clone = function() {
        return new Point(this.x, this.y);
    };
    Point.prototype.length = function(length) {
        if (typeof length == 'undefined')
            return Math.sqrt(this.x * this.x + this.y * this.y);
        this.normalize();
        this.x *= length;
        this.y *= length;
        return this;
    };
    Point.prototype.normalize = function() {
        var length = this.length();
        this.x /= length;
        this.y /= length;
        return this;
    };
    return Point;
})();

/*
 * Particle class
 */
var Particle = (function() {
    function Particle() {
        this.position = new Point();
        this.velocity = new Point();
        this.acceleration = new Point();
        this.age = 0;
    }
    Particle.prototype.initialize = function(x, y, dx, dy) {
        this.position.x = x;
        this.position.y = y;
        this.velocity.x = dx;
        this.velocity.y = dy;
        this.acceleration.x = dx * settings.particles.effect;
        this.acceleration.y = dy * settings.particles.effect;
        this.age = 0;
    };
    Particle.prototype.update = function(deltaTime) {
        this.position.x += this.velocity.x * deltaTime;
        this.position.y += this.velocity.y * deltaTime;
        this.velocity.x += this.acceleration.x * deltaTime;
        this.velocity.y += this.acceleration.y * deltaTime;
        this.age += deltaTime;
    };
    Particle.prototype.draw = function(context, image) {
        function ease(t) {
            return (--t) * t * t + 1;
        }
        var size = image.width * ease(this.age / settings.particles.duration);
        context.globalAlpha = 1 - this.age / settings.particles.duration;
        context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size);
    };
    return Particle;
})();

/*
 * ParticlePool class
 */
var ParticlePool = (function() {
    var particles,
        firstActive = 0,
        firstFree = 0,
        duration = settings.particles.duration;

    function ParticlePool(length) {
        // create and populate particle pool
        particles = new Array(length);
        for (var i = 0; i < particles.length; i++)
            particles[i] = new Particle();
    }
    ParticlePool.prototype.add = function(x, y, dx, dy) {
        particles[firstFree].initialize(x, y, dx, dy);

        // handle circular queue
        firstFree++;
        if (firstFree == particles.length) firstFree = 0;
        if (firstActive == firstFree) firstActive++;
        if (firstActive == particles.length) firstActive = 0;
    };
    ParticlePool.prototype.update = function(deltaTime) {
        var i;

        // update active particles
        if (firstActive < firstFree) {
            for (i = firstActive; i < firstFree; i++)
                particles[i].update(deltaTime);
        }
        if (firstFree < firstActive) {
            for (i = firstActive; i < particles.length; i++)
                particles[i].update(deltaTime);
            for (i = 0; i < firstFree; i++)
                particles[i].update(deltaTime);
        }

        // remove inactive particles
        while (particles[firstActive].age >= duration && firstActive != firstFree) {
            firstActive++;
            if (firstActive == particles.length) firstActive = 0;
        }


    };
    ParticlePool.prototype.draw = function(context, image) {
        // draw active particles
        if (firstActive < firstFree) {
            for (i = firstActive; i < firstFree; i++)
                particles[i].draw(context, image);
        }
        if (firstFree < firstActive) {
            for (i = firstActive; i < particles.length; i++)
                particles[i].draw(context, image);
            for (i = 0; i < firstFree; i++)
                particles[i].draw(context, image);
        }
    };
    return ParticlePool;
})();

/*
 * Putting it all together
 */
(function(canvas) {
    var context = canvas.getContext('2d'),
        particles = new ParticlePool(settings.particles.length),
        particleRate = settings.particles.length / settings.particles.duration, // particles/sec
        time;

    // get point on heart with -PI <= t <= PI
    function pointOnHeart(t) {
        return new Point(
            160 * Math.pow(Math.sin(t), 3),
            130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25
        );
    }

    // creating the particle image using a dummy canvas
    var image = (function() {
        var canvas = document.createElement('canvas'),
            context = canvas.getContext('2d');
        canvas.width = settings.particles.size;
        canvas.height = settings.particles.size;
        // helper function to create the path
        function to(t) {
            var point = pointOnHeart(t);
            point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350;
            point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350;
            return point;
        }
        // create the path
        context.beginPath();
        var t = -Math.PI;
        var point = to(t);
        context.moveTo(point.x, point.y);
        while (t < Math.PI) {
            t += 0.01; // baby steps!
            point = to(t);
            context.lineTo(point.x, point.y);
        }
        context.closePath();
        // create the fill
        context.fillStyle = '#ea80b0';
        context.fill();
        // create the image
        var image = new Image();
        image.src = canvas.toDataURL();
        return image;
    })();

    // render that thing!
    function render() {
        // next animation frame
        requestAnimationFrame(render);

        // update time
        var newTime = new Date().getTime() / 1000,
            deltaTime = newTime - (time || newTime);
        time = newTime;

        // clear canvas
        context.clearRect(0, 0, canvas.width, canvas.height);

        // create new particles
        var amount = particleRate * deltaTime;
        for (var i = 0; i < amount; i++) {
            var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());
            var dir = pos.clone().length(settings.particles.velocity);
            particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);
        }

        // update and draw particles
        particles.update(deltaTime);
        particles.draw(context, image);
    }

    // handle (re-)sizing of the canvas
    function onResize() {
        canvas.width = canvas.clientWidth;
        canvas.height = canvas.clientHeight;
    }
    window.onresize = onResize;

    // delay rendering bootstrap
    setTimeout(function() {
        onResize();
        render();
    }, 10);
})(document.getElementById('pinkboard'));
< / script>
< / BODY>
< / HTML>